Udyr has been a long time jungler of choice on OCE amongst the higher levels. It has now filtered down to the lower levels. Yi has been hot on OCE since Feral Flare got put into the game across all levels. I know the Feral Flare nerfs made their popularity decline in other regions, but not here.
Site to check rates for all regions
Note that for Oceania, across all leagues, Master Yi has been the 4th most banned champion over the last 7 days and Udyr is 6th. As well as the difference between those two being 30% with Yi's ban rate being 55%. People just don't like versing him - the snowball potential from slack teamplay in solo queue is just too great. LeBlanc is #1 at 80%.
And if you don't believe me about Rengar, check his played rate in Challenger for Oceania. 12th for games played over last 7 days. Ryze is 6th most played.
Also interesting to note across most leagues, Morgana's win rate % is positive (above 50%). However, go to Challenger and Morgana falls to 43%. Also notable that any league below Challenger plays very high amounts of Vayne but has win rates of 44%-46% while she's mid-range for being played in Challenger but has a win rate of 60%. Also notable that Lee Sin and Thresh are always in the top few most played but are well negative in win rates until you hit Diamond.
Challenger is very much dependent on what players are specialised in. My friend in Challenger on Oceania is a specialist on Riven. The pros will generally stick to their usual role and go with their usual suspects or something they want to learn up.